If Vilma did that he's guilty as charged. It doesn't matter where the money came or if they never intended to actually pay the money, if Vilma threw 10 grand on the table said that it goes to whoever knocks Favre out of the game, then he's guilty.
Agreement to injure means people involved understand within the context that there was an agreement to injure (see, I can double-speak like goodell).
If Vilma said "I give 2 high-fives to anybody who <fill in the blank with whatever potty mouth football players say> Favre/Warner" and everybody involved understood those statements are figurative, not literal, there are no agreement to injure.
GW declaration repeatedly stated there were no agreement to injure, that nobody involved in the program understood they could received award only for injuring another player.
If one want to play semantics game on whether Vilma phrasing could be construed as a pledge for injury, good luck getting an independent arbitrator or a federal judge to buy that slippy slope logic.
The only issue is -- was there an agreement to injure. Only those involved can say if there was an agreement. And all the players who had spoken out said there were no agreement to injure. Just because an outsider think they meant something else doesn't matter.